Canine coronavirus vaccine

ABSTRACT

A new pantropic canine coronavirus (CCoV) strain, having reduced pathogenicity, and capable of eliciting an immune response, is described.

FIELD OF THE INVENTION

The isolation of a novel pantropic canine coronavirus (CCoV) strain is described along with the production of a novel immunogenic composition comprising the CCoV strain. The strain is characterised at molecular and biological levels by, inter alia, sequence analysis.

BACKGROUND OF THE INVENTION

Coronaviruses are large, enveloped, single-strand RNA viruses that cause respiratory and/or enteric disease in mammals and birds (18). In dogs, three coronaviruses have been described so far. Canine coronavirus (CCoV) type I and type II are enteric viruses belonging to the antigenic group 1 (13), whereas canine respiratory coronavirus (CRCoV), first reported in UK by Erles et al. (19), is a group-2 coronavirus causing respiratory distress especially when associated to other pathogens (1, 9).

Type I and II CCoVs are widely distributed in Europe (7, 14) and are usually responsible for the appearance of mild to moderate gastroenteritis in pups, although death can occur as a consequence of simultaneous infections by both genotypes (5) or by other pathogens (3-11). Single CCoV infections are restricted generally to the gastroenteric tract, leading to the appearance of anorexia, diarrhoea and vomiting (Tennant et al., 1991).

Because of the widespread infections associated with CCoV, a need exists for vaccines capable of protecting against CCoV infections in canines.

SUMMARY OF THE INVENTION

The present invention provides an isolated pantropic canine coronavirus (CCoV) that does not express a functional accessory protein 3c. More particularly, the CCoV strain also does not express a functional accessory protein 3b. In another embodiment, the isolated CCoV strain comprises an isolated polynucleotide having at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof. In another embodiment, the CCoV strain is inactivated by chemical treatment or heating. In another embodiment, the CCoV strain is attenuated. In another embodiment, the isolated CCoV comprises SEQ ID NO: 5.

The present invention further provides an isolated polynucleotide from a canine coronavirus (CCoV), wherein said isolated polynucleotide has at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof. More particularly, said polynucleotide does not encode for a functional accessory protein 3c. In another embodiment, said polynucleotide does not encode for a functional accessory protein 3b. In another embodiment, the isolated polynucleotide consists of SEQ ID NO: 1 or a complementary strand thereof.

Another embodiment of the present invention provides an isolated polypeptide from a CCoV or plurality of polypeptides encoded by a polynucleotide having at least 95% homology to SEQ ID NO: 1. More particularly, the polynucleotide does not comprise the CB/05 strain polynucleotide. In another embodiment, said polypeptide has at least 95% homology to any one of SEQ ID NOs: 2-10. More particularly, said polypeptide is selected from any one of SEQ ID NOs: 4 or 5. More particular still, said polypeptide is SEQ ID NO: 5.

Another embodiment of the present invention provides an immunogenic composition comprising at least one of: (a) the polynucleotide, the polypeptide or the isolated canine coronavirus (CCoV) described herein; and a pharmaceutically acceptable excipient, diluent, carrier protein or adjuvant. In another embodiment, the immunogenic composition comprises an inactivated or attenuated form of the isolated canine coronavirus (CCoV). In another embodiment, the immunogenic composition comprises an isolated polypeptide from a CCoV or plurality of polypeptides encoded by a polynucleotide having at least 95% homology to SEQ ID NO: 1, wherein said polypeptide(s) are subunit antigens of the isolated CCoV. In another embodiment, the composition does not comprise an accessory protein 3c. In another embodiment, the composition does not comprise an accessory protein 3b.

Another embodiment of the invention provides an immunogenic composition as described above, for use in the treatment or prevention of a coronavirus infection in a dog. Another embodiment provides for use of the immunogenic composition in the preparation of a medicament for treatment or prevention of a coronavirus infection in a dog. Another embodiment provides a method of treating or preventing a coronavirus infection in a dog comprising administering the immunogenic composition in an amount effective to create an immunogenic response in the dog.

Another embodiment of the invention provides a canine coronavirus (CCoV) vaccine comprising at least one of: (a) a polynucleotide described above, (b) the polypeptide described above and/or (3) the isolated canine coronavirus (CCoV) strain described above.

These and other embodiments, features, and advantages of the invention will become apparent from the detailed description and the appended claims set forth herein below.

BRIEF DESCRIPTION OF THE FIGURE

The FIGURE illustrates the phylogenetic relationships of the novel CCoV strain described herein. At the phylogenetic level, strain 450/07 clustered with strain CB/05 in both S and M/N protein sequences, although a strict relatedness with recombinant CCoV/TGEV strains (CCoV-IIb) detected recently was also evident in the M/N sequences.

DETAILED DESCRIPTION

In 2005, a pantropic variant of CCoV (strain CB/05) was isolated from the internal organs of some dead pups (2) and the virus was classified as a hypervirulent biotype of CCoV-II, sharing with reference strains belonging to this genotype a high degree of genetic homology (9-12). Few aa changes in the S protein, including a Asp/His to Asn mutation at residue 125, and a 38-nt deletion in ORF3b were suggested as potential markers for the high pathogenicity of strain CB/05 (9-12). The virus isolate was demonstrated to full-fill the Koch's postulate through experimental infection of CCoV seronegative pups, that displayed severe clinical signs, including marked lymphopenia, and mortality (13). In a subsequent experiment, a striking finding was observed. In fact, seropositive dogs recovered from a recent infection caused by an enterotropic CCoV strain were susceptible to a subsequent experimental challenge with strain CB/05, showing mild clinical signs and lymphopenia (14). This may account for a limited cross-protection against the pantropic variant of enteric CCoV and, consequently, of currently available CCoV vaccines that are prepared with enteric strains.

In the present application, we have isolated a novel pantropic CCoV strain from the lungs of a pup that had died after systemic disease. The virus was characterised at the genetic level, displaying a close relatedness (more than 99% of aa identity) to the prototype strain CB/05 in all proteins encoded by the 3′ end of the viral genome. Amino acid 125 of the S protein exhibited an Asn residue exactly as strain CB/05 and the 38-nt deletion in ORF3b was also confirmed, but the novel strain displayed an additional 164-deletion in ORF3c that likely prevented synthesis of the encoded accessory protein. Coronavirus accessory protein genes are believed to be dispensable for replication in vitro, but they are strictly maintained during infection of the natural hosts (26). In both pantropic CCoV strains, accessory protein 3b was truncated (22 instead of 71 aa encoded by the same gene of other CCoVs) and in the most recent one (450/07) the ORF3c product was unlikely synthesised due to the presence of an early stop codon in the 5′ end of the gene. Similar deletions in the accessory protein genes of feline coronavirus have been suggested to play a certain role in the enhanced virulence showed by its hypervirulent biotype feline infectious peritonitis virus (21). The close genetic relatedness observed between strains CB/05 and 450/07 is consistent with the hypothesis that the novel strain is a direct descendant of the prototype virus. Enterotropic CCoV-II strains genetically related to CB/05 have been detected in recent years, but none of them displayed deletions in accessory protein genes (9-12). Thus, strain 450/07 may have been originated from the prototype virus through an additional 164-nt deletion in ORF3c.

At the biological level, isolates CB/05 and 450/07 were both able to infect pups and spread to their internal organs, causing systemic disease and lymphopenia. However, despite their close genetic relatedness, the two viruses showed different degrees of pathogenicity. Under experimental conditions, the prototype virus caused a severe form of disease, with the death of two out five infected pups, whereas the novel strain induced only mild to moderate clinical signs in the majority of the challenged pups. Importantly, lymphopenia was more marked in pups infected with strain CB/05 (reaching lymphocytes counts below 60% of the baseline values in all animals) than in those challenged with the novel pantropic strain that displayed an evident reduction of lymphocyte numbers only in few pups. In addition, compared to strain CB/05, the post-mortem findings induced by the novel virus were less severe and even the viral RNA titres in the faeces and internal organs were lower. This behavior may suggest a lower pathogenic potential for dogs of strain 450/07 with respect to the prototype pantropic isolate. The isolation of a new pantropic CCoV strain from a dead pup is noteworthy from an epidemiological point of view as it seems to suggest that this variant is circulating in dogs. The pantropism and lymphopenic attitude of strain CB/05 have been demonstrated (albeit at a less extent) also for the new isolate 450/07 and this biological behavior has been tentatively associated to few unique genetic changes (presence of Asn at residue 125 of the spike protein). The circulation of a CCoV cluster with pantropic and lymphopenic attitude stresses the need to develop homologous vaccines on the basis of the poor cross-protection induced by enteric CCoV (14).

Thus one embodiment of the instant invention provides a vaccine or immunogenic composition comprising a CCoV strain that does not express a functional accessory protein 3c. Another embodiment provides an isolated canine coronavirus (CCoV) that does not express a functional accessory protein 3c. More particularly, the isolated CCoV comprises a polynucleotide having at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof. In another embodiment, the isolated CCoV comprises a polypeptide having SEQ ID NO: 5. In another embodiment, the isolated CCoV comprises a polypeptide having SEQ ID NO: 4. In another embodiment, the isolated CCoV comprises a polypeptide having any one of SEQ ID NOs: 2 or 6-10. In another embodiment, the isolated CCoV is inactivated by chemical treatment or heating, attenuated or is in purified subunit form.

Another embodiment of the present invention provides an isolated polynucleotide from a canine coronavirus (CCoV), wherein said isolated polynucleotide has at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof. In another embodiment, said polynucleotide does not encode for a functional accessory protein 3c. In another embodiment, said polynucleotide does not encode for a functional accessory protein 3b.

In another embodiment, said polynucleotide consists of SEQ ID NO: 1 or a complementary strand thereof.

Another embodiment of the present invention provides a composition comprising an isolated polypeptide of SEQ ID NO: 5.

Another embodiment provides immunogenic composition comprising at least one of: (a) the isolated canine coronavirus (CCoV); (b) the isolated polynucleotide; and/or (c) the polypeptide as described herein; and a pharmaceutically acceptable excipient, diluent, carrier protein or adjuvant.

In another embodiment, the immunogenic composition is for use in the treatment or prevention of a coronavirus infection in a dog. Another embodiment provides for use of the immunogenic composition in the preparation of a medicament for treatment or prevention of a coronavirus infection in a dog. Another embodiment provides a method of treating or preventing a coronavirus infection in a dog comprising administering the immunogenic composition in an amount effective to create an immunogenic response in the dog.

Finally, another embodiment provides a canine coronavirus (CCoV) vaccine comprising (a) the isolated canine coronavirus (CCoV); (b) the isolated polynucleotide; and/or (c) the polypeptide as described herein.

ACRONYMS AND DEFINITIONS

The following acronyms and definitions are used throughout the application, unless indicated otherwise. In accordance with this detailed description, the following abbreviations and definitions apply. It must be noted that as used herein, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an antibody” includes a plurality of such antibodies, and reference to “the dosage” includes reference to one or more dosages and equivalents thereof known to those skilled in the art, and so forth.

ACRONYMS

-   -   aa amino acid     -   CaHV canid herpesvirus     -   CCoV canine coronavirus     -   CDV canine distemper virus     -   CPE cytopathic effect     -   CPV canine parvovirus     -   CRM₁₉₇ diphtheria toxoid cross-reactive material 197 (gly52glu)     -   D-MEM Dulbecco's minimal essential medium     -   EDTA ethylenediaminetetraacetate     -   FCA Freund's complete adjuvant     -   IFA incomplete Freund's adjuvant     -   h hour     -   i.m. intramuscular     -   IF immunofluorescence     -   i.p. intraperitoneal     -   i.v. intravenous     -   IgG immunoglobulin G     -   ISCOM immunostimulating complexes     -   KLH Hemocyanin from Megathura crenulata (“keyhole limpet”)     -   KMUA N-k-maleimidoundecanoic acid     -   KMUS (N-[k-maleimidoundecanoyloxy]sulfosuccinimide ester)     -   L liquid     -   LPS lipopolysaccharide     -   LT heat labile toxin     -   MDP muramyl dipeptide, also known as         N-acetyl-muramyl-L-alanyl-D-isoglutamine     -   min minutes     -   NO not observed     -   orf open reading frame     -   p.o. orally     -   PBS phosphate buffered saline     -   PBST PBS with Tween 20     -   Poly rA:Poly rU poly-adenylic acid-poly-uridylic acid complex     -   POP-POE polyoxypropylenepolyoxyethylene     -   PT pertussis toxin     -   RAS Ribi™ adjuvant system     -   RPM revolutions per minute     -   s.c. subcutaneous     -   TCID50 median tissue culture infective dose     -   TGEV transmissible gastroenteritis coronavirus (Purdue Strain)     -   TNF tumor necrosis factor     -   WBC white blood cells     -   wk week     -   wt weight

DEFINITIONS

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The following terms are provided below.

An “immunogenic composition” is a preparation containing an immunogen, including, e.g., a protein, a peptide, a whole cell, inactivated, subunit or attenuated virus, or a polysaccharide, or combination thereof, administered to stimulate the recipient's humoral and cellular immune systems to one or more of the antigens present in the immunogenic composition. “Immunization” is the process of administering an immunogenic composition and stimulating an immune or immunogenic response to an antigen in a host. Preferred hosts are mammals, such as dogs.

An “immune response” refers to the activities of the immune system, including activation and proliferation of specific cytotoxic T-cells and B-cells resulting in antigen-specific antibody production, after contact with an antigen.

An “antigen” is any agent, e.g., a protein (or immunogenic fragments of proteins such as a fragment of an adhesion protein), a peptide or peptide conjugate, immunogen, or a polysaccharide, that elicits an immune response. In this instance, the antigen preferably comprises a coronavirus antigen. The immunogenic composition can comprise one or more coronavirus antigens or immunogens.

A “unit dose” is a defined and predetermined concentration or amount of the immunogenic composition that is safe and effective to elicit an immune response in the recipient of the composition.

The term “subunit” refers to a a suspension of antigenic materials that is separated from the virulent host organism.

The term “therapeutic” as used herein means a treatment and/or prophylaxis. A therapeutic effect is obtained by suppression, remission, prevention or eradication of a disease state caused by CCoV.

The term “effective amount” as used herein means an amount that is determined by such considerations as are known in the art for vaccination and/or treating coronavirus infections (e.g., CCoV infections), wherein it is effective to provide measurable relief in treated subjects, such as exhibiting improvements including, but not limited to, improved survival rate, more rapid recovery, improvement or elimination of symptoms, reduction of post infectious complications and, where appropriate, antibody titer or increased titer against the infectious agent, and other measurements as known to those skilled in the art (e.g., measured via a blood sample).

The term “isolated” refers to a substance that is either in substantially pure form, for example, greater than about 95% purity; or purified in some way from its natural environment. An “isolated” strain (e.g. CCoV) indicates a strain that is removed from its natural environment, such as from a host animal/dog, and/or in a growth media. The term “isolated” encompasses immunogens or CCoV strains that are in solution with other agents/diluents/excipients/adjuvants.

“Parenteral” administration of an immunogenic composition includes, e.g., subcutaneous (s.c.), intravenous (i.v.), intramuscular (i.m.), or intrasternal injection or infusion techniques.

“Pharmaceutically acceptable” means a material that is not biologically or otherwise undesirable, i.e., the material can be administered to a subject without causing unacceptable biological effects (i.e. death) or interacting in a deleterious manner with any of the other components of the composition in which it is contained.

By “adjuvant” is meant a substance that serves to enhance the immunogenicity of an immunogenic composition. Thus, adjuvants are often given to boost the immune response and are well known in the art. Desirable characteristics of adjuvants include: (1) lack of toxicity; (2) ability to stimulate a long-lasting immune response; (3) simplicity of manufacture and stability in long-term storage; (4) ability to elicit both cell-mediated immunity (CMI) and humoral immune response (HIR) to antigens administered by various routes, if required; (5) synergy with other adjuvants; (6) capability of selectively interacting with populations of antigen presenting cells; (7) ability to specifically elicit appropriate Th1 or Th2 cell-specific immune responses; and (8) ability to selectively increase appropriate antibody isotype levels (e.g., IgA) against antigens.

Thus, the immunogenic compositions as described herein also comprise, in certain embodiments, one or more adjuvants. An adjuvant is a substance that enhances the immune response when administered together with an immunogen or antigen. A number of cytokines or lymphokines have been shown to have immune modulating activity, and thus are useful as adjuvants, including, but not limited to, the interleukins 1-α, 1-β, 2, 4, 5, 6, 7, 8, 10, 12 (see, e.g., U.S. Pat. No. 5,723,127), 13, 14, 15, 16, 17 and 18 (and its mutant forms); the interferons-α, -β and -γ; granulocyte-macrophage colony stimulating factor (GM-CSF) (see, e.g., U.S. Pat. No. 5,078,996 and ATCC Accession Number 39900); macrophage colony stimulating factor (M-CSF); granulocyte colony stimulating factor (G-CSF); and the tumor necrosis factors α and β. Still other adjuvants that are useful with the immunogenic compositions described herein include chemokines, including without limitation, MCP-1, MIP-1α, MIP-1β, and RANTES; adhesion molecules, such as a selectin, e.g., L-selectin, P-selectin and E-selectin; mucin-like molecules, e.g., CD34, GlyCAM-1 and MadCAM-1; a member of the integrin family such as LFA-1, VLA-1, Mac-1 and p150.95; a member of the immunoglobulin superfamily such as PECAM, ICAMs, e.g., ICAM-1, ICAM-2 and ICAM-3, CD2 and LFA-3; co-stimulatory molecules such as CD40 and CD40L; growth factors including vascular growth factor, nerve growth factor, fibroblast growth factor, epidermal growth factor, B7.2, PDGF, BL-1, and vascular endothelial growth factor; receptor molecules including Fas, TNF receptor, Flt, Apo-1, p55, WSL-1, DR3, TRAMP, Apo-3, AIR, LARD, NGRF, DR4, DR5, KILLER, TRAIL-R2, TRICK2, and DR6; and Caspase (ICE).

Suitable adjuvants used to enhance an immune response further include, without limitation, MPL™ (3-O-deacylated monophosphoryl lipid A, Corixa, Hamilton, Mont.), which is described in U.S. Pat. No. 4,912,094. Also suitable for use as adjuvants are synthetic lipid A analogs or aminoalkyl glucosamine phosphate compounds (AGP), or derivatives or analogs thereof, which are available from Corixa (Hamilton, Mont.), and which are described in U.S. Pat. No. 6,113,918. One such AGP is 2-[(R)-3-Tetradecanoyloxytetradecanoylamino]ethyl 2-Deoxy-4-O-phosphono-3-O—[(R)-3-tetradecanoyoxytetradecanoyl]-2-[(R)-3-tetradecanoyloxytetradecanoyl-amino]-b-D-glucopyranoside, which is also known as 529 (formerly known as RC529). This 529 adjuvant is formulated as an aqueous form (AF) or as a stable emulsion (SE).

Still other adjuvants include muramyl peptides, such as N-acetyl-muramyl-L-threonyl-D-isoglutamine (thr-MDP), N-acetyl-normuramyl-L-alanine-2-(1′-2′ dipalmitoyl-sn-glycero-3-hydroxyphosphoryloxy)-ethylamine (MTP-PE); oil-in-water emulsions, such as MF59 (International PCT Publication No. WO 90/14837) (containing 5% Squalene, 0.5% Tween 80, and 0.5% Span 85 (optionally containing various amounts of MTP-PE) formulated into submicron particles using a microfluidizer such as Model 110Y microfluidizer (Microfluidics, Newton, Mass.)), and SAF (containing 10% Squalene, 0.4% Tween 80, 5% pluronic-blocked polymer L121, and thr-MDP, either microfluidized into a submicron emulsion or vortexed to generate a larger particle size emulsion); incomplete Freund's adjuvant (IFA); aluminum salts (alum), such as aluminum hydroxide, aluminum phosphate, aluminum sulfate; Amphigen; Avridine; L121/squalene; D-lactide-polylactide/glycoside; pluronic polyols; killed Bordetella; saponins, such as Stimulon™ QS-21 (Antigenics, Framingham, Mass.), described in U.S. Pat. No. 5,057,540, ISCOMATRIX (CSL Limited, Parkville, Australia), described in U.S. Pat. No. 5,254,339, and immunostimulating complexes (ISCOMS); Mycobacterium tuberculosis; bacterial lipopolysaccharides; synthetic polynucleotides such as oligonucleotides containing a CpG motif (e.g., U.S. Pat. No. 6,207,646); IC-31 (Intercell AG, Vienna, Austria), described in European Patent Nos. 1,296,713 and 1,326,634; a pertussis toxin (PT) or mutant thereof, a cholera toxin or mutant thereof (e.g., International PCT Publication Nos. WO 00/18434, WO 02/098368 and WO 02/098369); or an E. coli heat-labile toxin (LT), particularly LT-K63, LT-R72, PT-K9/G129; see, e.g., International PCT Publication Nos. WO 93/13302 and WO 92/19265.

Exemplary conventional carrier proteins can also be used with the immunogenic compositions/antigens/CCoV strains described herein. Carrier proteins are preferably proteins that are non-toxic and non-reactogenic and obtainable in sufficient amount and purity. Carrier proteins should be amenable to standard conjugation procedures. In a particular embodiment, CRM₁₉₇ is used as the carrier protein. In other embodiments, a carrier protein of the invention is an enzymatically inactive streptococcal C5a peptidase (SCP) (e.g., one or more of the SCP variants described in U.S. Pat. Nos. 6,270,775; 6,355,255; and 6,951,653). Other suitable carrier proteins include inactivated bacterial toxins such as tetanus toxoid, pertussis toxoid, cholera toxoid (e.g., CT E29H, described in International PCT Publication No. WO2004/083251), E. coli LT, E. coli ST, E. coli DnaK protein, and exotoxin A from Pseudomonas aeruginosa. Bacterial outer membrane proteins such as outer membrane complex c (OMPC), porins, transferrin binding proteins, pneumolysin toxin (e.g., U.S. Pat. No. 5,565,204), pneumolysin toxoid (e.g., International PCT Publication No. WO 2005/108580) pneumococcal surface protein A (PspA), pneumococcal adhesin protein (PsaA), or Haemophilus influenzae protein D, can also be used. Bacterial heat shock proteins, such as mycobacterial hsp-70 can also be used. Other proteins, such as Staphylococcus epidermidis proteins SdrG, SitC and ferrochrome binding proteins, and Staphylococcus aureus proteins ClfA, ClfB and FnbA can also be used. Still other proteins, such as ovalbumin, keyhole limpet hemocyanin (KLH), glutathione S-transferase (GST), bovine serum albumin (BSA), galactokinase (galK), ubiquitin, β-galactosidase, influenza NS1 protein, or purified protein derivative of tuberculin (PPD) can also be used as carrier proteins. Virus-like particles, for example from rotavirus VP6 or from bacteriophage Qβ, can also be used.

One of skill in the art can readily select an appropriate carrier for use in this context. Methods for coupling compounds to carrier proteins are known in the art. See, e.g., ED HARLOW AND DAVID LANE, ANTIBODIES: A LABORATORY MANUAL (1988); and GREG T. HERMANSON, BIOCONJUGATE TECHNIQUES (Academic Press 1996).

The compositions disclosed can be administered in a variety of ways. It should be noted that the pharmaceutical composition containing the immunogen(s) can be administered alone or in combination with one or more pharmaceutically acceptable carriers, stabilizers, preservatives, colorants, flavorants, and excipients.

The CCoV and related compositions disclosed can be formulated with conventional carriers and excipients, which are selected in accord with ordinary practice. Aqueous formulations are prepared in sterile form, and when intended for delivery by routes other than oral administration, generally are isotonic. All formulations optionally contain excipients such as those provided for example in the HANDBOOK OF PHARMACEUTICAL EXCIPIENTS (5th ed., Raymond C. Rowe et al., eds., 2006). Excipients include ascorbic acid and other antioxidants, chelating agents (e.g., EGTA and EDTA), carbohydrates (e.g., dextrin), hydroxyalkylcellulose, hydroxyalkylmethylcellulose, stearic acid, and the like. The pH of the formulations ranges from about 3 to about 11, but is ordinarily about 7 to about 10.

Examples of physiologically acceptable carriers for routes of administration other than oral administration include but are not limited to saline solutions (e.g., normal saline, Ringer's solution, PBS (phosphate-buffered saline); polysorbate 80; L-arginine; polyvinylpyrrolidone; α-D-glucopyranosyl; α-D-glucopyranoside (trehalose); and combinations, thereof. For example, trehalose can be present in the composition in an amount from about 2 to about 10% weight/volume of the composition. In another example, when trehalose and polysorbate 80 are both present in the composition, trehalose can be present in the amount of about 4 to about 6% wt./vol. and the polysorbate 80 can be present in the amount of about 0.001 to 0.01% (wt./vol.) and generally mixtures of various physiologically compatible salts including potassium and phosphate salts with or without sugar additives (e.g., glucose).

Suitable excipients for use in the immunogenic formulations are, for example, water, saline, dextrose, glycerol, and ethanol. Non-toxic auxiliary substances, such as wetting agents, buffers, stabilizers, or emulsifiers can also be added to the composition.

Parenteral administration, if used, is generally characterized by injection. Sterile injectables can be prepared in conventional forms, either as liquid solutions or suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions.

Methods of Treatment and Administration

For each recipient, the total amount of the composition necessary for administration can be derived from protocols for immunization. The exact amount of such immunogenic compositions required may vary from dog to dog, depending on the breed, age, weight, and general condition of the dog, its mode of administration, whether it is administered with another antigen, adjuvant and the like. Generally, dosage will approximate that which is typical for the administration of other immunogenic compositions.

The immunogenic composition is typically administered as a sterile composition. The immunogenic composition can be administered by any suitable means, e.g., parenteral (including subcutaneous, intramuscular, intravenous, intradermal, perilymphatic, intranasal, intrapleuric, intrapulmonary, intrathecal, and epidural) or orally. Other routes include rectal, nasal, intranasal, topical (including buccal and sublingual), and vaginal. It is appreciated that the preferred route can vary with, for example, the condition of the recipient. An appropriate evaluation of the time and method for delivery of immunogenic compositions is well within the skill of the clinician/veterinarian. For example, the first dose can be administered at the elected date and a second dose can follow several weeks to several months from the first dose. Additional booster doses of the original immunogenic composition or modified forms can be administered as necessary (e.g., annually).

While it is possible for the active ingredients to be administered alone, it can be preferable to present them as immunogenic formulations. The formulations may include at least one active ingredient together with an acceptable carrier, excipients, adjuvants and/or, optionally, other non-active and/or active ingredients.

The formulations include those suitable for the foregoing administration routes. The formulations can conveniently be presented in unit dosage form and can be prepared by any of the methods well known in the art of pharmacy. Techniques and formulations generally are found in REMINGTON'S PHARMACEUTICAL SCIENCES (Mack Publishing Co., Easton, Pa.). Such methods include the step of bringing into association the active ingredient with the carrier, which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.

The oil phase of the emulsions of this invention can be constituted from known ingredients in a known manner. While the phase can comprise merely an emulsifier (otherwise known as an emulgent), it desirably comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier, which acts as a stabilizer. It is also preferred to include both an oil and a fat.

Emulients and emulsion stabilizers suitable for use in the formulation of the invention include but are not limited to Tween® 60 (as well as other polyoxyethylene sorbitan ester surfactants), Span® 80, cetostearyl alcohol, benzyl alcohol, myristyl alcohol, glyceryl mono-stearate, and sodium lauryl sulfate.

Formulations suitable for nasal administration have a particle size, for example, in the range of 0.1 to 500 microns (including particle sizes in a range between 0.1 and 500 microns in incremental microns such as 0.5, 1, 30, 35, etc.), which is administered by rapid inhalation through the nasal passage. Suitable formulations include aqueous or oily solutions of the active ingredient. Squalene is an exemplary carrier.

Formulations suitable for parenteral administration include aqueous and nonaqueous, isotonic, sterile injection solutions that can contain antioxidants, buffers, bacteriostats, and solutes, which render the formulation isotonic with the blood of the intended recipient, and aqueous and nonaqueous sterile suspensions that can include suspending agents and thickening agents.

The formulations are presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and can be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, water for injection, immediately prior to use. Injection solutions and suspensions are prepared from sterile powders, and granules of the kind previously described.

Veterinary carriers are materials useful for the purpose of administering the composition and can be solid, liquid or gaseous materials, which are otherwise inert or acceptable in the veterinary art and are compatible with the active ingredient. These veterinary compositions can be administered orally, parenterally, or by any other desired route.

A formulation of the present invention can be administered to the patient-dog in an injectable formulation containing any compatible carrier, such as various vehicles, adjuvants, additives, and diluents; or the compounds utilized in the present invention can be administered parenterally to the patient in the form of slow-release subcutaneous implants or targeted delivery systems such as polymer matrices, liposomes, and microspheres. An implant suitable for use in the present invention can take the form of a pellet, which slowly dissolves after being implanted, or a biocompatible delivery module well known to those skilled in the art. Such well-known dosage forms and modules are designed such that the active ingredients are slowly released over a period of several days to several weeks.

The compounds and compositions can also be used in combination with other active ingredients. Such combinations are selected based on the condition to be treated, cross-reactivities of ingredients, and pharmacological properties of the combination. Additionally, the compositions and compounds described herein can also be administered in conjunction with other conventional agents used to treat viral infections, such as antivirals, antipyretics, immunogens and analgesics. These compounds and compositions can be administered together with, or in the same course of, therapy with the compounds and compositions described herein. The individual components of the combination can be administered either sequentially or simultaneously in separate or combined pharmaceutical formulations.

Passive Immunity Therapies

Another aspect provided herein are methods and compositions for treating a subject to induce passive immunity. Compositions comprising an immunotherapeutic agent against nosocomial infections can be prepared and administered to the subject animal. The plasma from the immunized animal is then collected, and a hyperimmune globulin harvested from the plasma that contains anti-CCoV and, if included, other anti-carrier protein antibodies. The hyperimmune globulin can be used for inducing passive immunity to coronavirus infections.

The immunogenic compositions are administered to a subject-dog to induce a humoral immune response. The recipient then acts as a source of immunoglobulin (i.e., hyperimmune immunoglobulin) that is produced in response to the immunogenic composition. The immunized subject-dog donates plasma, from which the hyperimmune globulin is then obtained via, for example, conventional plasma fractionation technology. The fraction comprising anti-CCoV antibodies can then be administered to another subject-dog in order to impart resistance against or to treat a canine coronavirus infection.

For a more clear understanding, and in order to illustrate the invention more clearly, specific examples thereof are set forth hereinbelow. The following examples are merely illustrative and are not to be understood as limiting the scope and underlying principles of the invention in any way.

EXAMPLES A. Clinical Case

A 60-day-old miniature pinscher died after displaying systemic disease characterised by fever (39.5-40° C.), leucopenia (4.7×10⁹ cells/l, reference range 6-17×10⁹ cells/l), mainly lymphopenia (0.5×10⁹ cells/l, reference range 1.0-4.8×10⁹ cells/l), lethargy, anorexia, vomiting and haemorrhagic diarrhoea. The puppy had been administered, ten days before death, a single dose of a vaccine containing canine parvovirus, canine distemper virus, canine adenovirus type 2, Leptospira canicola and Leptospira icterohaemorrhagie. A supportive therapy with antibiotics (amoxicillin/clavulanic acid) and fluids (lactated Ringer's solution) did not succeed in any improvement of the clinical conditions that continued to deteriorate until the pup's death.

Necropsy revealed gross lesions in the alimentary tract (haemorrhagic enteritis), tonsils (necrotic areas), lungs (fibrinous pneumonia), liver (enlargement and areas of necrosis), spleen (enlargement) and kidneys (degeneration of the cortex). During post-mortem examination, samples were collected from brain, lungs, spleen, liver, mesenteric lymph nodes, kidneys, and intestinal content.

B. RNA/DNA Extraction

For RNA purification, the tissue samples were homogenised (50% w/v) in Dulbecco's minimal essential medium (D-MEM) using a Tissue lyser (QIAGEN S.p.A., Milan Italy), whereas the intestinal content was homogenised (10% wt/vol) in D-MEM by vortexing. After a brief centrifugation at 8,000×g for 3 min, 140 μl of the supernatants were submitted to RNA extraction using the QIAamp® Viral RNA Mini Kit (QIAGEN S.p.A.). DNA was extracted from the tissue samples and intestinal content by DNeasy Tissue Kit and QIAamp Viral RNA Mini Kit (QIAGEN S.p.A., Milan, Italy).

C. Virological Investigations

Intestinal contents and tissue samples collected from the dead dog were tested for molecular detection of the main viral pathogens of dogs, such as CCoV (4, 5), reoviruses (Leary et al., 2002), rotaviruses (20), caliciviruses (24), canine parvovirus type 2 (CPV-2) (7, 8), canine adenoviruses type 1 and type 2 (23), canine distemper virus (CDV) (17), canid herpesvirus type 1 (CaHV-1) (31).

D. Real-Time RT-PCR Assays for CCoV Characterisation

Characterization of the CCoV genotypes was carried out by means of type-specific real-time RT-PCR assays (5, 6). Reverse transcriptions and real-time PCR amplifications were performed as for CCoV detection, but with different sets of primers/probes: primer pair CCoVI-F (CGTTAGTGCACTTGGAAGAAGCT)/CCoVI-R (SEQ ID NO:11) (ACCAGCCATTTTAAATCCTTCA) (SEQ ID NO:12) and probe CCoVI-Pb (FAM-CCTCTTGAAGGTACACCAA-TAMRA) (SEQ ID NO:13) were used for CCoV type I detection, whereas primer pair CCoVII-F (TAGTGCATTAGGAAGAAGCT)/CCoVII-R (SEQ ID NO:14) (AGCAATTTTGAACCCTTC) (SEQ ID NO:15) and probe CCoVII-Pb (FAM-CCTCTTGAAGGTGTGCC-TAMRA) (SEQ ID NO:16) were employed for CCoV-II detection. The thermal profile consisted of activation of iTaq DNA polymerase at 95° C. for 10 min, followed by 45 cycles of denaturation at 95° C. for 15 s, annealing at 53° C. (CCoV type I-specific assay) or 48° C. (CCoV type II-specific assay) for 30 s and extension at 60° C. for 1 min.

E. Amplification and Sequence Analysis of the Genomic 3′ End from the CCoV-Positive Lung Sample

The 3′ end of the genome of the pantropic CCoV strain detected in the lungs was amplified using SuperScript™ One-Step RT-PCR for Long Templates (Life Technologies, Invitrogen srl, Milan, Italy), as previously described (9, 10, 11). Seven partially overlapping fragments were amplified that encompass ORFs 2 (S gene), 3a, 3b, 3c, 4 (E gene), 5 (M gene), 6 (N gene), 7a and 7b. The PCR-amplified products were sequenced by Genome Express (Meylan, France) and the obtained sequences were assembled and analyzed using the BioEdit software package (22) and the NCBI's (http://www.ncbi.nlm.nih.gov) and EMBL's (http://www.ebi.ac.uk) analysis tools. Nucleotide sequences obtained in this study were deposited in the GenBank database (http://www.ncbi.nlm.nih.gov) under accession number GU146061. The nucleotide (nt) sequences of the different ORFs were converted into amino acid (aa) sequences, that were used for comparative analysis with the prototype pantropic CCoV strain CB/05 (GenBank accession number DQ112226) and reference coronavirus strains. Phylogenetic and molecular evolutionary analyses were conducted using Mega3 (25). Phylogenetic trees, based on the S and M-N proteins of strain 450/07 were elaborated using both parsimony and neighbor-joining methods, supplying a statistical support with bootstrapping over 1000 replicates.

F. Virus Isolation

The lung of the dead pup was homogenised (10% w/v) in D-MEM together with antibiotics (penicillin 5000 IU/ml, streptomycin 2500 μg/ml, amphotericin B 10 μg/ml), and inoculated into canine fibroma (A-72) cells. Infected cells were monitored daily for the occurrence of cytopathic effect (CPE) and, after 5 days of incubation, they were tested for CCoV antigen by an immunofluorescence (IF) assay using a monoclonal antibody targeting the N protein (courtesy of Dr. Gill Chappuis, Merial, France).

G. Experimental Infection of Dogs

Nine 10-11-week-old antibody-profile defined beagles from the same litter were used for this challenge study after an acclimatization period of seven days. The study was conducted at the isolation unit of the Animal Hospital, Faculty of Veterinary Medicine of Bari (Italy) according to the animal health and well-being regulations and was authorized by the Italian Ministry of Health (authorization no. 57/2006-C). All animals were seronegative to CCoV by ELISA and by PCR test from rectal swabs collected before study start (day −10 and day −1). Dogs were also negative to a CPV shedding PCR test from rectal swabs, but had been vaccinated in the kennel against CPV and tested positive to CPV serum antibodies. Dogs were housed in individual cages in three separate rooms at their arrival for acclimation and then re-allocated on day −3 through randomization in two different groups (T01 and T02, Table 1).

TABLE 1 Study design: treatment groups and challenge material Treatment Number of Animal Group animals ID Challenge Material T01 3 9315 Cryolysate of 9317 A-72 cells 9321 T02 6 9316 CCoV 450/07 9318 (3^(rd) passage on 9320 A-72 cells) 9314 9319 9322

Each dog was individually housed for the administration of the challenge and to monitor clinical signs. All animals were weighed on study day −3, −1, 3, and 5. On study day 0, the 6 dogs in treatment group T02 were challenged with a total volume of 4 mL (3.0 mL orally and 1.0 mL intra-nasally; 0.5 mL per nostril) containing 10⁵ TCID₅₀/mL of strain 450/07 (3^(rd) passage on A-72 cells). Three control dogs in group T01 received the same volume of a cryolysate of uninfected A-72 cells by the same route of administration. All dogs were monitored daily for clinical signs by the attending veterinarian starting on day −1 (before challenge) and for as long as the animals remained in the study. The general health of each animal was assessed using the scoring system described in Table 2. Scores were used to assess the general health of individual animals and their treatment groups.

TABLE 2 Scoring system for general health observations during the challenge trial Parameter Result Score General Normal 0 appearance Depressed/Lethargic 2 Difficulties in breathing 3 Death 20 Dehydration None (<4%): not detectable 0 Mild (4-5%): subtle loss of skin elasticity 1 Moderate (6-8%): definite delay in return of skin to 2 normal position; eyes possibly sunken in orbits; slightly prolonged capillary refill time; possibly dry mucous membranes Severe (10-15%): tented skin standing in place; 3 prolonged capillary refill time; eyes sunken in orbits; dry mucous membranes possible signs of shock (increased heart rate, weak pulses); death imminent Diarrhea None 0 Soft 1 Liquid 2 Bloody 3 Rectal 37.0-39.4° C. 0 temperature ≧39.5° C. 2 ≦37.0° C. 3 Body Weight loss 2 weight No weight loss 1 Weight gain 0

Blood samples were collected from each dog. EDTA-blood and serum samples were collected from the jugular vein on study days −3, 0 (pre-challenge), 3, and 5 (day of necropsy) for complete and differential blood cell counts and detection of CCoV antibodies, respectively. Rectal temperatures (° C.) were measured at arrival, on study day −3, and then daily until study day 5. Nasal and rectal swabs were collected on study days −3, −1, 3, and 5.

Five days post-challenge, all dogs were sedated by intravenous administration of 10 mg/kg of body weight of Zoletil® 100 (Virbac S.r.l., Italy) and euthanized by intravenous administration of 0.5 mL/kg of body weight of Tanax® (Intervet Italia, Italy). During necropsy, samples for virus isolation and real-time RT-PCR were collected from small intestine, mesenteric, intermandibular and popliteal lymph nodes, lung, liver, spleen, and kidney. Fresh tissue samples were collected in D-MEM and RNA Later Solution (QIAGEN S.p.A.) for viral isolation and real-time RT-PCR assays, respectively, and kept at −70° C. until used.

EDTA-blood samples and faecal swabs collected intra-vitam, as well as tissue samples collected at necropsy examination, were tested for CCoV by virus isolation on A-72 cells (9, 13) and/or by real-time RT-PCR (3, 4). CCoV antibodies were searched for in the serum samples by ELISA and virusneutralisation tests, as previously described (29; 13).

Results H. Identification of a CB/05-Like Strain in Internal Organs of the Dead Dog

The intestinal content and tissue samples of the dead dog (450/07) tested negative for all viral pathogens with the exception of CCoV. By real-time RT-PCR (Decaro et al., 2004), the highest viral RNA load (5.81×10⁶ RNA copies/μL of template) was found in the lung sample, but the virus was also detected in the intestinal content (8.57×10⁵ RNA copies/μL of template), mesenteric lymph nodes (2.31×10⁵ RNA copies/μL of template), spleen (1.78×10⁴ RNA copies/μL of template), liver (3.43×10³ RNA copies/μL of template), kidney (7.09×10³ RNA copies/μL of template). Only traces of CCoV RNA (4.36×10¹ RNA copies/μL of template) were detected in the brain sample. The virus (strain 450/07) was characterized as CCoV-II by means of the genotype-specific TaqMan assays (5, 6).

The lung sample having the highest viral was used for virus isolation attempts, that were already successful at the first passage, as confirmed by occurrence of CPE and positive staining by the IF assay. Three serial passages were carried out in order to obtain a stock virus of strain 450/07 for the challenge experiment, which had a titre of 10⁵ TCID₅₀/mL of viral suspension. The stock virus was tested for the presence of other viral pathogens of the dog and for sterility from aerobe and anaerobe bacteria, mycoplasmas and mycetes and no contaminant agent was detected.

The 3′ end of the genome of strain 450/07 was amplified from the lung material through amplification of seven overlapping fragments. The obtained sequence was 8,618 nt long and contained the full length of ORFs 2, 3a, 3b, 3c, 4, 5, 6, 7a and 7b. The S protein (ORF2 product) was 1454-aa long exactly as that of prototype strain CB/05, to which the new pantropic isolate was highly related at this level (99.5% aa identity). A high degree of genetic relatedness was found also in the other structural proteins, including the E (82 aa, 100% identity), M (262 aa, 99.2% identity) and N (382 aa, 99.7% identity) proteins, encoded by ORFs 4, 5, and 6, respectively. Products of ORFs 3a (71 aa), 3b (22 aa), 7a (101 aa) and 7b (213 aa) were intact with respect to prototype strain CB/05. The 38-nt deletion in ORF3b found in strain CB/05 was also detected in strain 450/07, which exhibited an additional 164-nt deletion in ORF3c. This deletion was responsible for a change in the frame shift and the consequent introduction of a very early stop codon at nt 4824 of the sequenced genomic region that should prevent the synthesis of the ORF3c product.

At the phylogenetic level, strain 450/07 clustered with strain CB/05 in both S and M/N protein sequences, although a strict relatedness with recombinant CCoV/TGEV strains (CCoV-IIb) detected recently (16) was also evident in the M/N sequences (FIGURE).

I. Clinical, Post-Mortem and Virological Findings in Experimentally Infected Dogs

A summary of all the clinical sings recorded daily is shown in Table 3.

TABLE 3 Summary of clinical signs observed on study days (D) in control dogs (T01) and in dogs experimentally infected with strain 450/07 (T02) Treat. Body weight Enlargement group Dog ID Depression Diarrhea¹ Dehydration² Fever D −1 vs. D3/D5 of lymph nodes Other T01 9315 NO NO NO NO Gain NO NO 9317 NO NO NO NO Gain NO NO 9321 NO NO NO NO Loss NO NO T02 9316 NO NO NO NO Loss D5 NO 9318 D5 D4(S) NO NO Loss D5 NO D5(S) 9320 NO D4(S) NO NO Loss D5 NO 9314 NO NO NO NO Loss D4, D5 Decreased capillar refill and pale mucosa (D5) 9319 NO D5(S) D5(M) D4 Loss D4, D5 NO 9322 D4, D5, D3(S), D4(L) D4(S) NO Loss D3, D4, D5 Nasal secretion D4(S) (D1, D2, D4) NO, Not observed. ¹S, soft; L, liquid. ²M, moderate; S, severe.

All six dogs in T02 and one of three control dogs in T01 lost weight on day 3 after challenge compared to their (baseline) weight on day −1 (before challenge). Rectal temperature in T01 and T02 dogs ranged between 37.6° C. and 38.9° C. from day −8 to day 0 before challenge. For T01 dogs, rectal temperature after challenge ranged from 37.6° C. to 38.4° C., but for T02 dogs, the range after challenge increased to be between 37.6° C. and 39.5° C. However, only one dog (9319) from T02 group had fever on day 4, but three more dogs in T02 showed a numerical increase in their rectal temperature within the normal range after challenge. This change in range was not observed in T01 control dogs. Two dogs in T02 challenged with strain 450/07 were found depressed or lethargic on days 3 and 4 after challenge and two dogs of the same group were mildly to severe dehydrated on days 3 and 4 after challenge. Soft faeces or diarrhoea were observed in four T02 dogs on days 3 and 4 after challenge. All six dogs in T02 had lymphadenomegalia on days 3, 4 or 5 in one of the dogs (9322), on days 4 and 5 on two dogs (9314 and 9319) and on day 5 in the other three dogs. Dog 9322 had also nasal secretion on days 0, 1 and 4 post challenge and dog 9314 had decreased capillar refill and pale mucosa on day 5. Based on the scoring system reported in Table 2, two of the three control pups had a clinical score of zero because they did not show any clinical signs. One of the T01 dogs lost weight on days 3 and 5 after challenge but did not show any other clinical sign. This pup had therefore a score of 4 with its group showing a mean score of 1.3. However, all six pups in T02 group showed a variety of clinical sings, which lasted between one and three days and therefore their scores ranged from 2 to 19 (mean 5.7).

Day −3 and Day 0 lymphocyte and WBC counts per μL were averaged and were used as baseline levels to compare to the day 3 post-challenge levels. Lymphocyte counts decreased ≧30% in five dogs in T02, but less than 30% in the rest of dogs in T02 and T01. WBC counts decreased ≧30% in four of six dogs in T02, but less than ≧30% the dogs left in T02 and in all the control dogs (T01) (Table 4). The reduction in the lymphocyte counts were particularly dramatic for dog 9322 (75% with respect to the baseline values), that was the one that started showing clinical signs earlier and also showed the most severe clinical signs.

TABLE 4 Percentage reduction in lymphocyte and WBC counts on day 3 after challenge in control dogs (T01) and in dogs experimentally infected with strain 450/07 (T02) % Group Group Treatment Dog Lymphocyte mean % WBC mean group ID reduction (%) reduction (%) T01 9315 6 6.3 2 12 9317 2 0 9321 11 22 T02 9316 40 48.6 20 33.83 9318 22 39 9320 54 52 9322 75 37 9319 47 32 9314 54 23

At necropsy, four infected pups displayed mild to severe enteritis in one or more intestinal segments and five presented enlargement of the mesenteric lymph nodes, that were congested and with scattered haemorrhages (Table 5). Splenomegaly and involvement of popliteal and/or intermandibular lymph nodes were observed in one (9314) and two pups (9314 and 9322), respectively. Lung congestion and haemorrhages on the thymus were detected only in pup 9314, whereas in four pups abundant abdominal fluid was present. Consequently, a thymus samples and aliquots of the abdominal fluid were also collected from the lesions.

TABLE 5 Summary of post-mortem findings and virus detection in tissue samples of control dogs (T01) and of dogs experimentally infected with strain 450/07 (T02)^(a) Tr. Dog Other Mesenteric Abdominal grp ID LN LN Liver Lung Spleen Kidney Duodenum Jejunum Ileum fluid Thymus T01 9315 Neg Neg Neg Neg Neg Neg Neg Neg Neg NC NC 9317 Neg Neg Neg Neg Neg Neg Neg Neg Neg NC NC 9321 Neg Neg Neg Neg Neg Neg Neg Neg Neg NC NC T02 9316 Neg 1.68 × Neg Neg Neg 3.93 × Neg Neg 9.02 × NC NC 10^(3 (c)) 10¹ 10^(0 (c)) 9318 Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg^((c)) NC 9320 Neg 9.08 × Neg Neg Neg Neg Neg Neg Neg Neg^((c)) NC 10^(2 (c)) 9314 8.84 × 7.29 × 2.61 × 7.06 × 9.35 × Neg 7.41 × 5.93 × 2.16 × NC 1.22 × 10² (P)^((c)) 10^(5 (b,c)) 10² 10^(1 (c)) 10^(2 (c)) 10^(5 (b)) 10^(6 (b)) 10^(6 (b, c)) 10² 9319 Neg 2.80 × 2.01 × Neg 6.11 × 2.92 × 1.79 × 2.86 × 2.00 × 4.92 × NC 10^(6 (b, c)) 10¹ 10¹ 10² 10^(0 (c)) 10^(4 (c)) 10^(5 (b, c)) 10^(2 (c)) 9322 4.31 × 4.17 × 6.93 × Neg 1.51 × Neg Neg 2.45 × 3.33 × Neg^((c)) NC 10² (P)^((c)) 10^(6 (b,c)) 10⁰ 10⁰ 10^(2 (c)) 10^(2 (c)) LN, lymph node(s); (P), popliteal; Neg, negative; NC, not collected. ^(a)CCoV titres are expressed as RNA copy numbers per μL of template. ^(b)Tissues that tested positive by virus isolation. ^(c)Tissues that displayed gross lesions at post-mortem examination.

By real-time RT-PCR, three T02 pups were excreting virus on days 3 and/or 5 in their faeces, with titres ranging from 2.75×10³ to 1.07×10⁷ CCoV RNA copies per μL of template, and the viral RNA was detected in only one day 5 blood sample of a pup in T02 (titre of 5.73×10¹ RNA copies per μL of template). As expected on the basis of the viral loads, CCoV was only isolated from a day 3 rectal swab from pup number 9314 in T02 group. Several tissues collected from five infected pups tested positive by real-time RT-PCR, with the highest titres being detected in the lymphoid tissues (Table 5). CCoV was isolated from mesenteric lymph nodes in three dogs, from duodenum and jejunum in one dog and from Ileum in two dogs from T02. Neither nasal swabs from T02 dogs nor any samples from T01 dogs tested positive to CCoV by real-time RT-PCR or virus isolation.

By both ELISA and VN tests, seroconversion against CCoV was not detected in any control or challenged dogs.

The following references, discussed in relevant part supra, are hereby incorporated by reference as if set forth fully herein.

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1. An isolated canine coronavirus (CCoV) that does not express a functional accessory protein 3c.
 2. The isolated CCoV of claim 1, comprising an isolated polynucleotide having at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof.
 3. The isolated CCoV of claim 1, comprising a polypeptide having SEQ ID NO:
 5. 4. The isolated CCoV of claim 1, comprising a polypeptide having SEQ ID NO:
 4. 5. The isolated CCoV of claim 1, comprising a polypeptide having any one of SEQ ID NOs: 2 or 6-10.
 6. The isolated CCoV of claim 1, which is inactivated.
 7. The isolated CCoV of claim 1, which is attenuated.
 8. The isolated CCoV of claim 1, which is in purified subunit form.
 9. An isolated polynucleotide from a canine coronavirus (CCoV), wherein said isolated polynucleotide has at least 95% homology to SEQ ID NO: 1 or a complementary strand thereof, provided the polynucleotide does not comprise the CB/05 strain polynucleotide.
 10. The isolated polynucleotide of claim 9, wherein said polynucleotide does not encode for a functional accessory protein 3c.
 11. The isolated polynucleotide of claim 9, wherein said polynucleotide does not encode for a functional accessory protein 3b.
 12. The isolated polynucleotide of claim 9 consisting of SEQ ID NO: 1 or a complementary strand thereof.
 13. A composition comprising an isolated polypeptide of SEQ ID NO:
 5. 14. An immunogenic composition comprising the isolated canine coronavirus (CCoV) of claim 1 and a pharmaceutically acceptable excipient, diluent, carrier protein or adjuvant.
 15. The immunogenic composition of claim 14, which comprises an inactivated or attenuated form of the isolated CCoV.
 16. The immunogenic composition of claim 14, which comprises a subunit antigen of the isolated canine coronavirus (CCoV).
 17. The immunogenic composition of claim 14, wherein the composition does not comprise a functional accessory protein 3c.
 18. The immunogenic composition of claim 14 for use in the treatment or prevention of a coronavirus infection in a dog.
 19. Use of the immunogenic composition of claim 14 in the preparation of a medicament for treatment or prevention of a coronavirus infection in a dog.
 20. A method of treating or preventing a coronavirus infection in a dog comprising administering the immunogenic composition of claim 14 in an amount effective to create an immunogenic response in the dog.
 21. A canine coronavirus (CCoV) vaccine comprising the isolated canine coronavirus (CCoV) of claim
 1. 